Hemophagocytosis by leukemic blasts in 7 acute myeloid leukemia cases witht(16;21)(p11;q22) - Common morphologic characteristics for this type of leukemia

BACKGROUND. In a previous study of a case of acute megakaryoblastic leukemi a with t(16;21)(p11;q22), which displayed hemophagocytosis by leukemic blas ts, the authors mentioned that the same type of morphology had been cited i n the literature for 4 other cases of acute myeloid leukemia (AML) with the same translocation. This observation prompted the authors to examine more cases of AML with t(16;21)(p11;q22) for this morphology. METHODS. The authors reviewed bone marrow smears for the presence of hemoph agocytosis in 7 patients with AML identified as having t(16;21)(p11;q22). RESULTS. The leukemias belonged to the FAB-M1/M7 (n = 5), M5b (n = 2), and contained phagocytic blasts in various percentages (< 0.2-36.7%). The blast s contained either single or multiple cytoplasmic vacuoles, in some of whic h the phagosomes were visible. The engulfed hemopoietic cells (red cells, e rythroblasts, lymphocytes, and thrombocytes) were also noted in their cytop lasm. These observations confirmed that hemophagocytosis by leukemic blasts is a common and characteristic feature of this type of leukemia. CONCLUSIONS. The study of 12 cases (the 7 cases described here and the prev ious 5 cases) strongly supports the hypothesis that hemophagocytosis by leu kemic blasts is common and characteristic in this type of leukemia, which m ay he related to the specific chromosome aberration of t(16;21)(p11;q22). C ancer 2000;88: 1970-5. (C) 2000 American Cancer Society.